Digital rights management (DRM) is a class of access control technologies that are used by hardware manufacturers, publishers, copyright holders, and individuals to limit the use of digital content and devices. DRM may inhibit uses of digital content that are not intended by a content provider. Conditional access systems (CAS) are also a class of access control technologies that are used by content owners, service providers, and hardware manufacturers to limit the use of digital content and devices. Both DRM and CAS employ content encryption techniques, and methods to deliver the corresponding content encryption keys to valid receiver devices. The delivery of content encryption keys may involve the use of further protection techniques, and these techniques are assumed to be present any time a content encryption key is sent to a client device.